[REPOST PATCH] autofs - remove autofs dentry mount check

From: David Jeffery <redacted>

When checking if an autofs mount point is busy it isn't sufficient to
only check if it's a mount point.

For example, if the mount of an offset mountpoint in a tree is denied
for this host by its export and the dentry becomes a process working
directory the check incorrectly returns the mount as not in use at expire.

This can happen since the default when mounting within a tree is nostrict,
which means ingnore mount fails on mounts within the tree and continue. The
nostrict option is meant to allow mounting in this case.

Signed-off-by: David Jeffery <redacted>
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: stable@vger.kernel.org
---
 fs/autofs4/expire.c |    9 ---------
 1 file changed, 9 deletions(-)

diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index 01443ce..13ddec9 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c

@@ -61,15 +61,6 @@ static int autofs4_mount_busy(struct vfsmount *mnt, struct dentry *dentry)
 		/* This is an autofs submount, we can't expire it */
 		if (autofs_type_indirect(sbi->type))
 			goto done;
-
-		/*
-		 * Otherwise it's an offset mount and we need to check
-		 * if we can umount its mount, if there is one.
-		 */
-		if (!d_mountpoint(path.dentry)) {
-			status = 0;
-			goto done;
-		}
 	}
 
 	/* Update the expiry counter if fs is busy */